Machine for and method of lapping the ends of round work pieces



F. W. ELSTUB March 6, 1934.

MACHINE FOR AND METHOD OF LAPPING THE ENDS 0F ROUND WORK PIECES Filed Nov. 15, 1930 Jwomtoo Fi'nlvcla WILL/AM ELsrus Patented Mar. 6, 1934 UNITED STATES MACHINE FOR AND METHOD OF THE ENDS OF ROUND WORK PIECES Francis William Elstub, Coventry, England, as-

signor to Norton Company, Worcester, Mass, a corporation of Massachusetts I Application November 1930, Serial No.'495,948

In Great Britain January 1, 1930 I 7 Claims. (Cl. 51117) This invention relates to lapping machines and to a method of lapping duplicate work pieces which are particularly adapted for simultaneously lapping the end'f'aces of a multiplicity of du- 15 plicate pieces of round work, such as rolls of the type used in. roller bearings.

Rolls as commonly used in roller bearings must have extremely accurate surfaces and high finish upon each end face as well as upon their pe- 10 ripheries in order to provide accurate bearings of minimum friction. It is of prime importance that the end surfaces of frusto-conical or cylindrical rolls, for example, be accurately finished to lie in two parallel planes which are perpendicular to the respective axes of work rota-- tion to insure true and free rotation of the final assembled roller bearing. This condition is especially necessary in roller bearings which are designed to support an end thrust as well as'to support accurate axial rotation.

Heretofore, it has been extremely diflicult to accurately finish the opposite end faces of rolls so that they both are exactly parallel and square with their respective axes of rotation. In fact, the best accuracy obtainable under the prior average mass production methods has been only 75%. Since roller bearings are primarily designed to be used in precision machinery, this large percentage of error which scraps one out many inspection and testing operations on each roll before it has been deemed safe to assemble it within a finished bearing. For these reasons.

I mass production of rolls has been both slow and expensive.

It is therefore the primary object of my invention to provide a method of lapping and a lapping machine capable of carrying out the method whereby both end faces of a multiplicity of 40 duplicate rolls may be simultaneously ground to similar form. 1

It is another object of my invention to provide a work holding and guidingdevice adapted to be employed on various types of lapping machines whereby both end faces of a series of round work pieces secured thereto may be simultaneously lapped and particularly, whereby the end faces of cylindrical and frusto-conical pieces may be so lapped that they will lie in two exactly parallel planes which are square with the respective axes of work rotation.

It is still another object of my invention to provide a lapping machine having two opposed laps and a work guiding support therebetween so devised that a multiplicity of duplicate round of every four pieces of work has necessitated I rolling contact with "the peripheral surface of the shape and size. Thus, if both of the opposed lapwork pieces may be supported and rotated therein, thereby causing a simultaneous lapping operation upon both ends of each of said work pieces and finishing them so that each individual work piece has both of its end faces lying in parallel to planes whichv are perpendicular with its respective axis of work rotation;

Referring to the drawing which illustrates this invention and in which like reference numerals indicate like parts:

Fig. 1 is a'perspective view of the lapping machine which is broken away to show a multiplicity of work pieces mounted within the machine prior to a lapping operation; v

Fig. 2 is a sectional view taken through the winding spools which support the work retaining strap;

Fig. 3 is a detail, partly broken away, ofa modi fled form of support for the winding spools; and

Fig. 4 is a fragmentary view of a further modi- 76 fication showing an adjustable split metal ring arranged to secure the rolls against the driving disk. v

In accordance with my invention, 1 have provided a method and a machine for simultaneously finishing the opposed end faces of a multiplicity of duplicate round work pieces by engaging both end faces of all of the work pieces with two opposed laps which are movable relative to the work, and by holding said work pieces in positive rolling contact with a work driving disk which causes them to move through an ever changing path while in engagement with the laps. By maintaining each work piece in positive driving disk which has been finished to be an accurate surface of revolution, all of the work pieces are subjected to an identical abrading action and are consequently finished to precisely the same ping faces are parallel and if the driving disk is 7 rotated in a parallel plane therebetween, the op- These-lapping members may comprise annular no members of vitrified abrasive material, such as grinding wheels, or they may comprise metal plates charged with abrasive grains. Either or both or the lapping members may be stationary or rotatable insorar as the present invention is concerned and the driving (115K may b61110!- aole at a rate determmeo. by the nature of themovement imparted 50 the 0131181 members Of the machine, it being necessary that there be relative motion between the associated laps and the driving disk to rotate the work pieces and to cause them to move over the suriaces or the n In the form described, the upper lap is stationary and the disk and lower lap are rotated as shown in said prior patent. The driving disk 15 is supported for eccentric revolution relativeto the two opposed laps by means of the three revolving posts 16 which may also be arranged identically as shown in the prior patent to Indge. The upper stationary lap 14 may be conveniently supported in any way desired but is preferably secured to a plate 17 which is fastened by screws 19 to a spider member 20 fixed to the lower end of a shaft 22 which may be mounted for vertical movement toward and away from the work as shown in the aforementioned patent to Indge.

In order to locate the work in proper position for a correct lapping operation, there is provided a supporting means which maintains a series of round work pieces 24, having substantially the same size and shape, against the periphery of the driving disk 15 forrotation thereagainst. These work pieces are supported with their lower end faces resting upon the lower lap and are maintained with their peripheral surfaces in positive rolling contact with the peripheral surface of the driving disk 15 by means of a non-rotatable annular member which may be made adjustable to compensate for differences in size in the different groups of duplicate work pieces being lapped and to draw them into firm and accurate contact with the periphery of the driving disk. The form shown in Figs. 1, 2 and 3 comprises a flexible strap-like metal member 26 which is secured tangent to the work pieces by means of two spools 27 and 28 mounted upon a head 29 arranged to be moved adjacent to and with the eccentric movement of the driving disk 15. This head. 29 is pivotally and slidably supported from the main frame of the lapping machine so that it may freely float and follow the eccentric motion of the driving disk 15, thus maintaining the work pieces 24 in constant rolling contact between the rotatable disk 15 and the fixed strap 26.

To permit free floating of the strap 26 so that it may follow the eccentric motion of the driving disk, the head 29 has been pivotally fastened by means of a pin 31 to a member 33 which is slid- .main frame of the machine by screws 38. The

head 29 and strap 26 may be vertically adjusted to various heightsto accommodate different sizes of work by axially moving the two collars and 41 which are secured to stud 35 by screws 42 and 43 respectively and which locate the hub 34 upon stud 35. I v I To permit adjustment cf the strap 26 for work pieces of larger. or smaller diameter, one end thereof is secured to a fixed spool 28 by means of a screw 44 and the other end of strap 26 is secured by screw 45 to spool 27 which is rotatably adjustable. The spool 28 is fixedly mounted upon the head 29 by means of a'stud 47 and secured against rotation by means of pin 48. The spool 27 is rotatably, mounted upon head 29 by a stud 50 and is arranged for convenient angular ad justment by means of two pins 51 projecting therefrom. 1

To maintain the rotatable spool 27 in a locked position and thereby secure the strap 26 tangent to the peripheries of the work pieces so that each workpiece will be maintained in positive rolling contact with the driving disk 15, a brake mechanism is provided which comprises two brake shoes 53 and 54 shaped so as to engage each end of the strap 26 wound upon spools 27 and 28. When this strap has been adjusted to the correct tension byturning the spool 27, the machine operator may readily lock it in position by tightening screw 56 which connects two brake shoes 53 and 54 and causes them to clamp against both ends of strap 26 wound upon the spool thereby securely locking it in position.

A modified construction of my woik supporting mechanism is shown in Fig. 3 wherein I have provided a swinging arm 58 to support the pivot stud 31 and head 29 thereon'which is arranged to hold the two spools 2'7 and 28- upon which the retaining strap 26 is secured. The swinging arm 58is also pivotally mounted upon a link 59 by a connecting pin 61 and link 59 is pivotally secured upon stud 35 in the same manner as hub 34 is mounted, as illustrated in Fig. 1 of the drawing.

A further modification of my device is illus-' trated in Fig. 4 which shows an adjustable split annular member 63 which replaces the strap 26 shown in Fig. 1. This ring-like member 63 is provided with a split ear 64 radially projecting therefrom having a slotted portion 66 through which a fixed depending stud 67 projects and allows member 63 to follow the irregular motion' of driving disk 15 but prevents rotation thereof. To permit adjustment of ring member 63, the ends 68 of the split ring 63 are spaced apart and a screw 69 having a threaded portion screwed into one side of the ear 64 and rotatably engaging the other side of ear 64 is employed to draw the endstogether. Thus the machine operator may correctly maintain his work pieces in positive rolling contact with the driving disk 15 by moving the ends 68 by means of screw 69 and thereby adjust the inner surface of the ring member 63 which holds the work pieces against the driving disk 15. The depending stud 67 is fastened to a clamping member 70which is vertically adjustable upon the frame of the machine.

The operation of this machine is readily apparent from the foregoing disclosure. It is merely necessary to fill the space between the annular members 26 or 63 and the disk 15 with the duplicate work pieces 24. The operator may then angularly position the spool 27 (Fig. 1) and fix it in a locked position with the strap 26 tangentially engaging the work pieces 24 by tightening the screw 56 which serves to hold the brake drums 53 and 54 in binding contact against both ends of strap 26 and thereby maintain the spool 27 against rotation. If the operator is using such a device as illustrated in Fig. 4, heneed only adjust the screw 69 to such a position that 'the annular member 63 will maintain the work pieces 24 in positive rolling engagement with the disk 15. When these adjustments have been made, it is only necessary to lower the upper lap to rest upon the upper end surfaces of the work, whereupon the machine may be set in operation and the work pieces will be simultaneously lapped on both end faces. Upon completion of the lapping operation, the operator simply raises the upper lap by any convenient mechanism, loosens the strap 26 or the annular member 63 and removes the work pieces whereupon he may insert a new series of work blanks in position and continue as before.

By utilizing a work retaining member such as an adjustable strap 26 or an adjustable work retaining ring 63 to hold a multiplicity of duplicate work pieces in positive rolling contact with thework driving disk 15, the axes of all of the work pieces will be firmly maintained in the same angular relation with the axis of the'work driving disk since the peripheral surfaces of the driving disk and each work piece comprise accurate surfaces of revolution. Thus the axes of the work pieces will all maintain the same angular relation to the two opposed parallel lapping surfaces and a lapping operation caused thereby will form similar surfaces on the ends of each workpiece. If the axes of the work pieces are maintained parallel to the axis of the driving disk as is usually the case, the two opposed end faces upon all of the work pieces will be lapped to lie in exactly parallel planes which are perpendicular to their respective axes of work rotation.

My invention has proved to be an extremely accurate and practical method of rapidly and simultaneously lapping both end faces of a multiplicity of rolls to the same size. In fact, such extreme accuracy has been attained that a machine made in accordance with this invention has simultaneously lapped the end faces of a multiplicity of rolls such as used in roller bearing with such an extreme degree of perfection that it has been possible to pick up any ten rolls at random after completion of a lapping operation and make two adjacent piles of rolls of five each end upon end on a surface plate which fitted so accurately tangentially that they excluded the passage of light therebetween. Obviously when rolls can be continuously produced rapidly with such a high degree of accuracy by unskilled labor, a better quality of roller bearings can be manufactured at a lower cost under favorable mass production methods.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is: v I

l. A lapping machine comprising two opposed lapping'members and a circular driving disk interposed wholly therebetween which are relatively rotatable to perform a lapping operation, means. to positively rotate the driving disk, said disk having a peripheral surface, all elements of which have the same relation to its axis ofrotation, and an annular clamping member surrounding the disk and arranged to secure a multiplicity of duplicate round work pieces in positive continuous rolling contact with the entire peripheral surface on said driving disk and in simultaneous continuous abrading contact with both of said lapping members around the entire periphery of the driving disk whereby each work piece will be finished to exactly the same size.

2. A lapping machine comprising two opposed relatively rotatable lapping members and a rotatable work driving disk interposed therebetween having a cylindrical surface, all elements of which are parallel with and equidistant from its axis of rotation, a non-rotatable but adjustable annular member surrounding said disk and coaxial therewith and means to adjust said member, whereby it will maintain a multiplicity of duplicate round work pieces in continuous posirelatively rotatable lapping members and a circular rotatable work driving disk therebetween having a peripheral surface, all elements of which are equidistantfrom and bear the same angular relation to its axis of rotation, an adjustable, split annular member surrounding the disk and arranged to maintain a plurality of duplicate round work pieces in rolling contact therewith and means whereby the annular member may be adjusted to engage duplicate work pieces of different diameters and maintain them in positive rolling contactwith the peripheral face on said driving disk and in accurate. abrading engagement with both of the opposed laps whereby all of the work pieces may be finished to the same form and size.

4. A lapping machine comprising two opposed relatively rotatable lapping members and a circular, eccentrically driven, work driving disk therebetween having a cylindrical surface which moves through an ever changing path relative to the axes of the lapping members, a non-rober from rotating therewith, said member being arranged to maintain a. series of duplicate round workpieces in continuous positive rolling contact with said cylindrical surface whereby the ends of the work pieces will be supported in accurate and simultaneous abrading engagement with both of the opposed laps.

5. A lapping machine comprising two relatively rotatable lapping members having horizontally opposed parallel lapping surfaces, and a circular, eccentrically rotatable work driving disk therebetween which has a peripheral surface arranged to move through an ever changing path perpendicular to both of said lapping surfaces, a non-rotatable but adjustable annular member arranged to tangentially engage a plu-' rality of duplicate cylindrical work pieces andmaintain them in rolling contact with the peripheral surface on said driving disk, means to permit the annular member to freely float and follow the irregular motion of the driving disk but prevent rotation thereof and means whereby said annular member may be adjusted to hold various sizes of duplicate round work pieces in positive rolling contact with said driving disk and in lapping engagement with the opposed laps, whereby all of the work pieces will be simultaneously finished to the same size so that their end faces will lie in two parallel planes respectively which are perpendicular to their respective axes of work rotation. v

6. A lapping machine comprising two opposed laps providing abrasive annuli and a circular positively rotated driving, disk located therebetween, said members being so arranged and relatively moved at such rates that the work is caused-to travel through an ever changing path between the laps, the driving'disk having a. pc-

finished to lie in parallel planes which are perpendicular to the work axes.

7. A lapping machine comprising two opposed relatively rotatable lapping members and a rotatable work driving disk interposed wholly therebetween which has a peripheral surface, all elements of which are equidistant from and bear the same angular relation to its axis of rotation, a non-rotatable adj stable annular member arranged to support a plurality of duplicate round work pieces, means to adjust said member to hold all of the work pieces simultaneously against the periphery of the driving disk with a variable pressure and thereby maintain the work pieces in positive rolling contact with the disk, whereby all of the work pieces will be held in accurate lapping engagement with both lapping members and simultaneously finished to the same size.

FRANCIS WILLIAM ELSTUB.

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